Oglesby allen



Nov. 6, 1923. Re. 15,713 O. LLEN, JR`

S PARK' PLUG original Filed may 1v'. 1920 To all whom t may concern Reuma Nov. e, laas.

f Re.'15,113

PATENTV OFFICE.

OGLESBY ALLEN, JR., 0F CHICAGO, ILLINOIS, ASSIGNOB. TO ALLEN- SPCIALTY COM- PANY, OF CHICAGO, ILLINOIS, L CORPORATION OF ILLINOIS...

.sranx PLUG'.

' Original No. 1,894,523, dated October 25,1921, Serial No. 381,934, villei'l Hay 17, 1920. Application for reissue led July 130, 1923. ySerial No. 654,7195.

Be it known that I, OGLESBY ALLEN, Jr., la citizen of the United States, anda resident of Chicago, inthe county of Cook and State of Illinois,.have invented certain new and.

useful Improvements in Spark Plugs; and I do hereby declare that the following isa full,'clear, and exact description thereof, rellngs, and to the characters of reference marked thereon, which form a part of this speciication, v

. This invention relates to improvements in spark orignition plugs for the ignition s stems of explosion engines, and the'inventlon "consists in the combination and arrangement of the parts shown in the drawings `and de#v scribed in the specification, and is more particularly pointed out in the appended claims. Among the objects of the invention is 'to provide a spark plug which is made of few I to constructl and assemble, and which may` rugged and durable parts which are simple be made ata relatively low cost as compared to the eiliciency of the plug.

Another object .of the invention is to prol duce a spark plug which does not foul in operation 1n a manner to short circuit above the arcing pointsof the terminals, and in this respect .to provide means associated with the live terminal'above the sparking point thereof which acts as a heat retainer on the live terminal for the double purpose of retaining heat thereat and to avoid`cl1nging of carbon thereto, said heat retainer being of a material to avoid the deposit of carbon thereon.

A further object of the invention is to provide a construction and arrangement of the shell and porcelain insulator which will permit the insulator .to'be made relatively short so as to keep it away from the carbon depositing zone, and which, at the same time materially reduces the cost of the insulator.

A furtherobject of the invention is to im- Y prove the construction and arrangement of the grounded terminals, and es Figures 3 'and 4 are cross sections 'on the respective lines 3 3 and 4-4 10f- Figure 2. Figure 5 is a bottom end view of the plug. As shown insaid drawings: 10 ldesignates the metal shell of the plug,-

' 11 the porcelain, or other insulator, therein and extending upwardly from the top of" the shell, 12 a rod which extends' through an axial opening in the insulator and upwardly above the same, and extends below saidinsulator and the shell to constitute the live terminal 13 of the plug. Said rod is threaded and is held in placebetween a collar 14 at the lower end of the insulator and a nut 15 threaded to the rod above thejinsulator thatbears against an insulating washer 16 that lies upon theupper end of the insu-l lator. A threaded cap nut 17 engages the threaded rod above the -I1ut 15 to act with the nut 15 as a bindingscrew fora circuit wire at one side of the ignition circuit 18 designates the grounded terminals, there-being two in the construction shown arranged symmetrically with respect to the live terminal13.

The shell has an enlarged bore open at its top to receivea cylindric enlargement 20 of. the insulator, providing thereony upwardly and downwardly facing shoulders to oppose a shoulder 21 in tlie shell and the lower end of a nutA 22 that enters the enlarged bore `of the shell and is threaded thereto. axial displacement in the shell. Yielding Thus the insulator is held from washers are interposed between said shoulders on the insulator and the shoulder 21 and lower end of the nut 22 to avoid straining the insulator ina manner to check the same.

26 which terminates the proper sparking distance from the live terminal, and the said inturned portions26 are formed adjacent| to the live terminal with vertical sparking edges 27.

he collar 14; is threaded on the rod 12 ell and are dis- 'vertical shank 25l and an inturned portion and -is spaced from the lower end of the porcelain insulator by. an insulating .washer 28 of substantial thickness and of not less diameter than the lower end of said porcelain, The said collar bears at its lower end on a shoulder 29 formed, preferably,

integral with the rod 12, so that said collar is confined between said shoulder 29 and the washer 28 at the lower end of the porcelain The said collar is made of a material that will receive a high polish and one which will also retain heat under operating temperature, brass or otherv copper compound polished and under the temperature to which it will be subjected in operation of the plug acts to reject carbon deposit and is readily maintained unfouled over along period ot time. Moreover there is interposed between the upper larger end of the collar and the lower end of the insulator, which is tapered at said lower end with a terminal diameter not greater than the base of the conical collar and its associated insulating washer 28, which said insulating washer has the eect to prevent leakage of current from thecollar to any carbon deposit on the lowered taperedv end of the porcelain and thence to the 'grounded shell, the insulating washer 28 serving as a barrier against such leakage. Moreover the tapering ot' the lower end of the insulator serves furtherto minimize leakage of current from the collar '14 to the shell, because whatever carbon may lodge on the lower tapered end of the insulator is spaced a safe distance from the shell, even though there be a tendency to leakage from the collar 14 to carbon deposit on said tapered end of the insulator,

and the barrier between the upper larger end of the collar 14:, and carbon deposit at ythe* full diameter of the insulator is sufficiently great to be safe.

It will thus be seen that -the entire arrangement of the parts within the thin vwalled lower part of the shell goes toward barrier interference between 'the live'terminal and the metal parts associated therewith above the sparking point of the terminals,

so that sparking between the intended pointsy 'relatively long periods ot time. Thus there is assured great saving of time in keeping the spark plug in good firing condition, and is also assured tull snappy sparks that will ignite the compressed charges to the best advantage, and therebyY avoid wastage ot fuel due to detective non-sparking.

It will be noted that a spark plug possessing these advantages is simple, is rugged and long cost.

I claim l. A spark plug, comprising a shell, an insulator within said shell and terminating above the inner end thereof, so that an open chamber is left at the inner end of the shell, a terminal rod extending through said insulator and projecting beyond the inner end of the shell, and an inwardly tapering or conical metallic carbon-rejecting element surrounding said' terminal, said element having greater heat conductivity than said lived and can be made at small terminal and having a highly polished sure face. 2. A spark plug. comprising a shell, an

insulator within said shell and terminating above the innerend thereof, so that an open chamber is left a't theinner end of the shell, a terminal rod extending through said insulator and into the said chamber ot' the shell, and a metallic carbon-rejecting element surrounding said terminal, said element having high heat retaining properties relatively to said terminal and capable ot a highly polished surface.

3.-In a spark plug as set forth in claim 1, an insulating washer interposed between said metallic element and said insulator, said washer having a diameter not less than the base of said conical element, and being of substantial thickness to thereby serve as a-barrier to prevent leakage due to any carbon deposit between the inner e'nd of the incal metallic element. f

In testimony whereof I claim the foregoing as my invention, I hereunto append my signature at Chicago, Illinois, this 29th day of June, 1923.

oGLEsBY ALLEN, JR.4 

